By placing two Wi-Fi antennaes on the drone, Cheseaux says they
were able to locate mobile phones on campus to within 10 metres "in
the best tests we have performed". The drone uses the MAC address
of a phone to differentiate which device it is detecting and uses
several readings to attempt to calculate its location.

The proof-of-concept technology has numerous limitations,
including the fact that victims of disasters may be buried under
several metres of rubble, making the detection of mobile phone
signals difficult if not impossible.

Additionally, in less developed countries phones with Wi-Fi are,
at the moment, less common, raising the uncomfortable idea that
this technology would primarily help find wealthy victims at the
potential expense of less wealthy victims.

However, drone technology is increasingly being talked up as a
tool for disaster relief operations. As well as giving aid
organisations a cheap way of getting data from the air to scout out
an area, a use case championed by the UK-government backed Orchid
project, they can also be kitted out with existing detection
technology. These include thermal-imaging cameras, or in the case
of avalanches, specialised Avalanche
Victim Detectors (DVAs) -- radio devices mountaineers carry in
case they are buried by an avalanche.

"The drone's Wi-Fi antenna could be replaced by DVAs which would
enable the rapid and inexpensive deployment of the first avalanche
searches," said Cheseaux, an idea others have also
proposed.